Application study of Dynamic Mode Decomposition coupled with a high-speed imaging system in jet zone oscillation behavior diagnosis of impinging flames

Dynamic Mode Decomposition (DMD) is a data-driven analysis method for plenty of snapshots, which has good application prospects in the combustion diagnostics base on optical methods. In this study, the self-pulsation combustion instability of four-burner impinging diesel flame was explored based on a bench-scale opposed multi-burner entrained-flow gasifier. The spatiotemporal evolution of the flame structure in the jet zone was studied by DMD analysis. The vortex evolution of the central reaction stream was divided into four stages, and the period of each stage was determined. The boundary streams also have periodic oscillations in the reaction intensity. The modes with high growth factor can accurately identify the oscillation components in different structures of the flame. The corresponding feature DMD modes were in good agreement with the flame structure obtained from the grayscale image, but the local components in the DMD mode may belong to different time scales.